Gastric ring

ABSTRACT

The gastric ring comprises an elongate element that can be deformed into a loop between a distal end portion and a proximal end portion, together with closure means suitable for folding the elongate element into a loop and for fastening the distal and proximal end portions together once they have been moved close to each other while looping the ring. At least the elongate element is made of a material that is resorbable, preferably over a period of about or less than 2 years, e.g. of a poly-α-hydroxy acid. The elongate element is constituted by a proximal link, a distal link, and intermediate links hinged about pivot axes.

The present invention relates to a gastric ring, also known as agastroplasty ring or gastric band or a gastric constriction member.

BACKGROUND OF THE INVENTION

Fitting a gastric ring constitutes one of the techniques that have beendeveloped for combating massive obesity from which an increasing numberof people are suffering in developed countries.

Compared with other techniques, such as gastric bypass (BPG), orvertical banding gastroplasty (VGB), fitting a gastric ring presents theadvantage of not changing the anatomy of the patient. Its principle isto reduce the diameter of the stomach opening, creating an anteriorpocket of volume that is small so that the patient has a sensation ofbeing sated after ingesting a minimal quantity of food.

Since its appearance in 1986, several models of gastric ring have beenproposed that are suitable for being implanted by laparoscopic surgery.Nevertheless they all have structure that is substantially similar. Theycomprise a certain length of relatively narrow band made of a materialthat is sufficiently flexible to be capable of being looped, said bandbeing provided with closure means acting between its distal and proximalends. In addition, adjustment means suitable for being externallyactuated enable the inside diameter of the gastric ring to be adjusted,once it has been put into place.

In the ring known as a Lap Band® or as LAGB®, the adjustable nature isobtained by an inside section of the ring being inflatable, said sectionbeing the part that is to come into contact with the stomach. Aconnection tube connects said inflatable section to a so-called“injection port”. When the ring is put into place, the connection tubeand the connection part are permanently implanted inside the patient'sbody, with the injection port being easily accessible. While the ring isbeing put into place, it is at minimum inflation. Its diameter isadjusted by injecting the inflation fluid into the injection port.

The gastric ring known as the Swedish Adjustable Gastric Band SAGB®differs from the Lap Band® mainly by its closure system which consistsin a system having a tongue with a safety catch, the ring being closedby pulling on said tongue until the safety catch is reached. The ringknown under the name Heliogast® differs from the first two likewise byits closure system which makes use of hydraulic locking.

In spite of its recognized effectiveness, in terms of loss of weight,the gastric ring technique is not without drawbacks, in particular dueto the complications that can arise.

Some of these complications are associated with the presence of theinjection port which might be faulty, and with the connection tube whichmight rupture. According to a recent study, more than 8% of the observedcomplications are due to those two causes. Changing the injection portrequires further surgery under general anesthetic. A rupture in theconnection tube requires further laparoscopic surgery.

The injection port may also be the seat of acute or chronic suppuration.

Finally, in terms of appearance, implanting the injection port leaves ascar that is 5 centimeters (cm) to 6 cm long.

Other known complications of the gastric ring technique consist in aphenomenon whereby the ring migrates in the gastro-gastric wall, andalso in a phenomenon whereby the wall of the stomach slides through thering. Even though some complications of this kind can occur soon afterthe ring has been implanted, most of them appear in the medium term,after several years.

OBJECTS AND SUMMARY OF THE INVENTION

The object of the Applicant is to propose a gastric ring which mitigatesthe above-mentioned drawbacks in full or in part.

In conventional manner, the invention provides a gastric ring of thetype comprising an elongate element that is deformable into a loopbetween a distal end portion and a proximal end portion, and closuremeans suitable for folding said elongate element into a loop and forsecuring the distal and proximal end portions to each other once theyhave been brought close together by looping the ring.

In a manner characteristic of the invention, at least the elongateelement is made of a resorbable material.

The resorbable nature of the elongate element which constitutes the bodyof the gastric ring makes it possible to limit the presence of said ringover time and thus limits those complications which are associated withsuch presence in the medium and long term. In addition, thenon-definitive nature of fitting a ring of the invention has animportant psychological impact on the choice made by the patient. Aftera probationary period that is limited in time, the patient can stop theexperiment, or else, if so desired, proceed with a new implant that iseither definitive or else once again limited in time.

The elongate element is preferably made of a material that is resorbableslowly of a period of the order of or less than 2 years, and morepreferably over a period lying in the range 16 months to 24 months.

Firstly, this period of time corresponds to the period during whicheffective loss of weight takes place, prior to weight stabilizing.

Secondly, it is after this period that the presence of the gastric ringleads to increased risk in terms of migration, perforation, orinfection, in terms of progressive dilation of the esophagus, and interms of behavior disorders. These risks are thus eliminated by choosingthis resorption time.

The ring is essentially made of biodegradable materials of natural orsynthetic origin such as:

polylactide, polyglyoclide, poly ε-caprolactone;

polyhydroxybutyrate, polyhydroxyvalerate;

polycarbonates;

cellulose, polysaccharides, starch, . . . ;

. . . homopolymers, copolymers, and derivatives thereof.

The material constituting the elongate element is preferably apoly-α-hydroxy acid, which is a family of bioresorbable polymers.

Advantageously, amongst known poly-α-hydroxy acids, use is made of alactic polyacid, and more particularly a poly(L-lactide-co-D,L-lactide). At the final stage of degradation, lacticacid or glycolic acid are obtained, being respectively a metabolite anda pre-metabolite that are natural in the human body. These acids areoxidized in the organism into pyruvic acid which is itself metabolizedinto carbon dioxide gas and water via the tri-carboxylic acid cycle. Theelongate element of the gastric ring made of such a material is thuscompletely resorbed in the body of the patient. This resorption takesplace at a speed that varies as a function of various factors such aschemical composition and crystal content, molecular mass, and degree ofpolymerization. For example, the greater the crystal content of thelactic polyacid, the slower it is resorbed.

In an embodiment of the gastric ring of the invention, the elongateelement is constituted by a set of juxtaposed links. It is thus made upof a proximal link, a distal link, and intermediate links.

By way of example, each link is generally polyhedral in shape with aninner face for coming into contact with the stomach when the ring is putinto place, and two internal end faces, with at least those portionsthereof that are situated close to the inner face being oblique andconverging radially so that when the ring is closed all of said radialportions of the internal end faces are pressed one against another, andthe inner faces of the links constitute a substantially continuousconstriction surface.

In order to be suitable for being introduced by means of a trocar, it isnecessary for all of the intermediate links to be connected to oneanother. Each intermediate link preferably includes a shoulderprojecting from a first internal end face to form a pivot axis betweensaid link and a first adjacent link, and a recess in a second internalend face forming a housing for the shoulder of a second adjacent link,the shoulder and the recess being of dimensions that are suitable forbeing mutually interengaged.

The closure means must enable the elongate element to be looped toitself and the distal and proximal end portions to be connectedtogether, and in particular they must enable the distal link to beconnected to the proximal link.

In an embodiment, the closure means comprise at least one tie which issecured to at least one of the proximal and distal end portions.

Advantageously, said tie(s) is/are resorbable over a resorption periodthat is longer than the resorption period for the elongate element.

In this particular disposition, the gastric ring retains itseffectiveness even when the elongate element and in particular the linkshave lost a large fraction of their mechanical strength.

Optionally, said tie(s) is/are not resorbable, providing the presencethereof in the body of the patient after the elongate element has beenfully resorbed does not present any drawback, as is the case when thetie is to be found in a free state that is not tight about the stomach.This therefore applies when the tie does not interconnect the distal andproximal end portions.

In a preferred embodiment, using juxtaposed links to make up theelongate element, each link has two through holes forming two alignmentsof holes through the set of links so as to allow a single tie to passalong the elongate element twice, from the proximal link to the distallink via the first alignment of holes and then from the distal link tothe proximal link via the second alignment of holes. In order to causethe elongate element to become curved, it suffices to take hold of thetwo free ends of the tie and apply traction thereto, while keeping theproximal link in place so as to cause the distal link to move towardsthe proximal link, and then to knot the two free ends of the linktogether in order to hold the elongate element in its loopedconfiguration.

Preferably, in order to maintain the elongate element in its loopedconfiguration, the closure means include locking means formed, at leastin part, in the proximal and distal end portions of the elongateelement, and in particular in the proximal and distal links.

For example, one end portion has a male engagement element while theother end portion has a female engagement element. In particular, themale element may be a stud and the female element may be a recess. Whenapplied to links, the recess may be formed, for example, in an outer endface of the proximal or the distal link. While the ring is being putinto place, the links are curved in the form of a turn with the distallink moving to beside the proximal link, after which it suffices for theoperator to move said two links towards each other so as to engage thestud of one of them into the recess of the other, thereby locking thering.

In the embodiment where the closure means include a tie, advantageouslythe proximal end portion, possibly the proximal link, includes a tubefitting for passing the two free ends of the tie; this tube fitting ispreferably shaped to enable it to be secured to a ring introductionancillary. In particular, it may be threaded to enable it to bescrew-fastened to said ancillary. Under such circumstances, it is alsopreferable to provide a cap for closing the tube fitting, the cap beingpierced by a through hole for passing the two free ends of the tie, saidcap covering the threaded portion of the tube fitting after the ring hasbeen put into place and the ancillary has been withdrawn.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood on reading the followingdescription of an embodiment of a resorbable gastric ring, made up of ajuxtaposition of lactic polyacid links provided with a non-resorbableclosure tie, and shown in the accompanying drawings, in which:

FIG. 1 is a diagrammatic perspective view of the ring in its looped andlocked position;

FIG. 2 is a diagrammatic perspective view of an intermediate link;

FIG. 3 is a diagrammatic perspective view of the proximal link;

FIG. 4 is a diagrammatic perspective view of the distal link;

FIGS. 5, 6, and 7 show steps in putting the gastric ring into place,with the ancillary being shown in part; and

FIG. 8 is a diagrammatic perspective view of the gastric ring in thelooped state and carried by the ancillary.

MORE DETAILED DESCRIPTION

The gastric ring of the present invention is characterized by itstemporary nature, due to the fact that the elongate element constitutingthe main body of said ring is bioresorbable. Thus, unlike known gastricrings, the ring of the present invention is intended to constrict thestomach for a predetermined period only, without requiring new surgeryat the end of said period. The resorbable material is selected so as toenable the duration of said period to be adjusted. A preferred period isconsidered as lying in the range 16 months to 24 months, and in anyevent of the order of or less than 2 years. Nevertheless, this is notexclusive, and in particular circumstances it might be possible topropose gastric rings for temporary use of shorter or longer duration.

In the embodiment described below, the gastric ring is not adjustable insize. Nevertheless, the present invention is not limited to thisfeature. An adjustable gastric ring of structure analogous to that ofthe known rings outlined above, could present a predetermined operatinglifetime by virtue of its elongate element being made to bebioresorbable, by appropriately selecting the material from which saidelongate element is made, said material presenting the desiredbioresorbable nature. Nevertheless, under such circumstances, thereremain the drawbacks associated with the presence of special means forenabling the diameter of the ring to be adjusted, unless said means arelikewise made of a bioresorbable material.

Resorption of the ring, associated with its optionally non-adjustablenature, also gives rise to a reduction in cost, by virtue of reducing oreliminating certain post-operative checks, and thus by lowering the riskof complications associated with such checks, whether they involvetaking X-rays of the stomach, or making repeated punctures.

The gastric ring 1 described in greater detail below has its elongateelement made up of juxtaposed links, each link being a one-piece partmade of a bioresorbable rigid material that is also biocompatible.

In a specific embodiment, the selected bioresorbable material is apoly-α-hydroxy acid, and more precisely a lactic polyacid. This polymerloses its mechanical properties progressively until it is completelyabsorbed. It presents a skeleton that is sensitive to hydrolysis. It isdegraded by the combined effect of two phenomena, namely waterpenetrating into its matrix leading to short polymer chains being formedby breaking ester bonds, and migration or diffusion of these shortchains to the outside. With rigid one-piece parts such as the links ofthe present gastric ring, the diffusion coefficient of water through thepolymer matrix is greater than the migration coefficient of the productsof hydrolysis. As a result, degradation is observed to take place morequickly in the core of the link that at its periphery, so the gastricring remains effective during a longer period because it is its innerperiphery that applies constriction to the stomach.

At the final stage of resorption of the lactic polyacid, lactic acid orglycolic acid is/are obtained which are respectively a naturalmetabolite and a natural pre-metabolite of the human body. These lacticand glycolic acids are oxidized by the organism into pyruvic acid whichis itself metabolized into carbon dioxide gas and water, via thetri-carboxylic acid cycle.

Thus, the gastric ring of the present invention is completely resorbedin the body of the patient, with this resorption taking place at a speedthat is variable as a function of the characteristics of the resorbablematerial used.

With poly-α-hydroxy acid, the factors that influence resorption timeare, in particular, chemical composition and crystal content, molecularmass and degree of polymerization, the morphology of the part and inparticular whether the part is a one-piece part or a film, the residualmonomer content and the presence of possible other impurities, thedimensions of the part, the way in which it is sterilized, the sitewhere the polymer is implanted in the body, . . . . Amongst the factorsthat are the most important, it is important to observe the crystalcontent. The greater the crystal content of a poly-α-hydroxy acid, theslower it will be resorbed.

For a lactic polyacid, it is possible to have an influence on crystalcontent by using a copolymer based on the L-lactide monomer and theD,L-lactide monomer. Preferably, a copolymer is used having a molarratio of L-lactide to D,L-lactide that is of the order of 70/30 to80/20. Such a lactic polyacid loses its mechanical properties after afew months, but it is resorbed into the body only after a duration thatis considerably longer, and is a function in particular of the site inwhich it is implanted, and that duration may be of the order of 2 years,which is an appropriate duration as explained above.

In the example shown, the gastric ring 1 is made up of ten juxtaposedlinks, i.e. a proximal link 2, eight intermediate links 3, and a distallink 4.

In FIG. 1, the gastric ring 1 is shown in its configuration forconstriction around the stomach, with the set of juxtaposed links beingfolded to form a loop, the proximal and distal links 2 and 4 beinglocked together, with said folding into the form of a loop and saidlocking being obtained by closure means described in greater detailbelow.

In the example shown, it should be observed that the inner surface ofthe gastric ring 1 that comes into contact with the stomach is of apolygonal configuration having ten faces, i.e. it is not circular. Thisdisposition does not spoil the effectiveness of the ring in terms ofconstriction. It would be equally possible to attenuate this polygonalconfiguration by giving the inner faces 5 of each of the links 2, 3, 4 asomewhat concave shape.

FIG. 2 shows an intermediate link 3 seen in perspective. Theintermediate link 3 is generally in the form of a polyhedron havingthree determining faces, namely: its inner face 5 and two internal endfaces 7 and 7′, and more precisely the portions 6 and 6′ of theseinternal end faces 7 and 7′ that are situated close to the inner face 5.The inner face 5 (visible in FIG. 1) is for coming into contact with thestomach when the ring 1 is put into place. The portions 6, 6′ of the twointernal end faces 7, 7′ are oblique and converge radially so that whenthe ring 1 is closed, all of said radial portions 6, 6′, including thoseof the proximal and distal links 2 and 4, of said internal end faces arepressed one against another. The inner faces 5 of all of the links thusconstitute a substantially continuous surface for constricting thestomach.

It will be understood that for a gastric ring 1 made up of ten links, asin the example shown, the angle α formed between the two portions 6, 6′of the two internal end faces 7, 7′ needs to be 36°.

Given that the set of links making up the elongate element of thegastric ring 1 must be suitable for being introduced while in therectilinear state by using a trocar, it is necessary for the links to beconnected to one another. For this purpose, each intermediate link 3includes hinge and pivot elements constituted by a recess 8 and by ashoulder 9. The recess 8 is formed in the upper portion of the link,after the portion 6 and opens out into the outer face 10 and into theinternal end face 7. The shoulder 9 projects from the other internal endface 7′ in the upper zone of the link, after the portion 6′. The shapesof the recess 8 and of the shoulder 9 are such that the shoulder 9 of agiven intermediate link 3 is suitable for penetrating into the recess 8of the link that is immediately adjacent to the given link, while therecess 8 of the given link is suitable for receiving the shoulder 9 ofthe link that is immediately adjacent thereto.

In the example shown in FIG. 2, the shoulder 9 is constituted by acylindrical portion 9 a constituting the pivot axis for folding thevarious links during closure of the ring, and a connection portion 9 bbetween said cylindrical portion 9 a and the internal end face 7′ of thelink 3.

The recess 8 forms a cavity having a semicircular bottom 8 a forreceiving by mutual engagement the cylindrical portion 9 a of a shoulder9. This cavity 8 is open both to the internal end face 7 and also to theouter face 10 of the link 3, i.e. the face which is opposite from theinner face 5. This second opening 11 allows the connection portion 9 bof the shoulder 9 of the adjacent link to pass through when the variouslinks are hinged to one another. Each link, and in particular eachintermediate link 3, has two through holes 12 passing right through thelink between the two radial portions 6, 6′ of the internal end faces 7,7′.

FIGS. 3 and 4 show respectively the proximal link 2 and the distal link4. In these figures, the same references are used again for thoseportions that these links have in common with an intermediate link 3.

Like all of the intermediate links 3, the proximal link 2 has an interface 5, two through holes 12, and a shoulder 9 formed by a cylindricalportion 9 a and a connection portion 9 b. However it does have a recess8, with locking to the distal link 4 not taking place via a pivot hinge,but via specific locking means formed in the proximal link 2 and thedistal link 4 and suitable for co-operating with each other.

The locking means of the proximal link 2 consist in a female engagementelement 13 formed by a transverse recess 14 that is cylindrical, havingan inside wall provided with an abutment 15 that is partially annularand that projects towards the inside of the recess 14.

The proximal link 2 also has a tube fitting 16 pierced by a through hole17 and having its outer peripheral surface threaded, in order to enablethe proximal link 2 to be screw-fastened to an ancillary 26 for usewhile putting the gastric ring 1 in place.

It should be observed that unlike an intermediate link 3 or the distallink 4, the two through holes 12 do not open out into the secondinternal end face 6′, but into the transverse recess 14 in the throughhole 17.

Like all the intermediate links 3, the distal link 4 has a recess 8 withan opening 11, and two through holes 12 that are not visible in FIG. 4.

The locking means of the distal link 4 for locking with the proximallink 2 consist in a transverse stud 18 of generally cylindricalconfiguration, having a notch 19 subdividing said stud 18 into twobranches, a first branch 20 a at the end and a second branch 20 b thatis connected to the remainder of the distal link 4 via an intermediateportion 21. As can be seen clearly on examining FIG. 4, since the notch19 extends over only a fraction of the width of the link 4, the firstbranch 20 a at the end presents a degree of flexibility relative to thesecond branch 20 b. The ends 22 of the two branches 20 a and 20 b arechamfered so as to facilitate penetration of the stud 18 into the recess14 in the proximal link 2. In addition, towards said chamfered end 22,the flexible branch 20 a presents a partially annular groove 23 suitablefor receiving the abutment 15 of the proximal link 2.

In addition to the above-described locking means, the means for closingthe gastric ring 1 comprise means enabling the set of juxtaposed linksto be folded into the form of a loop so that the distal link 4 can comeup to and immediately beside the proximal link 2 so as to enable them tobe locked together. The folding means comprise a tie passing through thethrough holes 12 in all of the links, and also through the through hole17 in the tube fitting 16 of the proximal link 2. More precisely, whenthe links are in rectilinear alignment as shown in FIG. 5, the throughholes 12 constitute two parallel alignments for the tie 24. The tie 24passes firstly along one of the two alignments from the proximal link 2to the distal link 4, and then back along the other alignment from thedistal link back to the proximal link 2. The two free ends 25 and 25′ ofsaid tie 24 are passed together through the hole 17 in the tube fitting16 and also along the ancillary 26 which is screwed onto the tubefitting 16 and which is intended to enable the gastric ring 1 to be heldin its rectilinear configuration as shown in FIG. 5. Naturally, whilethe gastric ring is being introduced in this configuration, it isdisposed inside a trocar that is not shown in FIG. 5.

Given that the tie 24 is offset relative to the cylindrical portions 9 aof the shoulders 9 that act as pivot axes, when the practitioner exertstraction on the two free end 25, 25′, a traction force is exerted on thedistal link 2, thereby causing it to pivot about its pivot axis untilits internal end face 6 comes to bear against the internal end face 6′of the adjacent intermediate link, which is then caused to pivot, and soon until the entire set of links has folded completely to constitute aturn that is not yet closed.

FIG. 6 shows a portion of this turn, with the distal link 4 being closeto and immediately beside the proximal link 2. In this disposition, thestud 18 on the distal link 4 is facing the transverse recess 14. It thensuffices for the practitioner to use an appropriate instrument to movethese two links towards each other so as to cause the stud 18 topenetrate into the recess 14. The practitioner is assisted in thisaction by the chamfered shape 22 of the two branches 20 a and 20 b ofthe stud 18. During this penetration, and because of the chamfered shape22, the flexible branch 20 a goes beyond the abutment 15 until theabutment penetrates into the groove 23. This achieves complete andirreversible locking together of the proximal and distal links 2 and 4,and thus of the gastric ring 1 around the stomach. The practitioner canthen withdraw the ancillary 26 and can confirm that the gastric ring 1is in a closed configuration by making a tight knot between the two freeends 25 and 25′ of the tie 24 at the tube fitting 16. Optionally, theknot may be tied after the threaded tube fitting 16 has been coveredwith a closure cap 27 that is itself pierced by a hole 28 for passingthe two free ends 25 and 25′ of the tie 24.

In order to make it easier to move the proximal and distal links 2 and 4towards each other for locking purposes, with the practitioner thenusing equipment of the forceps type, the distal link 4 includes lateralgrooving 29 in the face of the distal link 4 that is level with the stud18 and remote from the notch 19. By positioning the ends of the twobranches of the forceps one in the grooving 29 in the distal link 4 andthe other in the opening 14 in the proximal link 2, the practitioner canensure that the two branches 20 a and 20 b of the stud 18 are accuratelypositioned facing the recess 14 when the distal and proximal links 4 and2 are face to face. It then suffices to move the two branches of theforceps towards each other to cause the stud 18 to penetrate into therecess 14 in order to achieve locking as described above.

The present invention is not limited to the specific embodimentdescribed above. The number, configuration, and dimensions of the linksare a function of the diameter of the constriction applied to thestomach. In the version described, this diameter is not adjustable, so aplurality of gastric ring models are made available to the practitionerso as to enable the most appropriate model to be selected for theparticular case that is to be treated.

Although not stated explicitly in the description above, it should beobserved that it is important to ensure that any ring configurationavoids presenting a sharp edge in order to avoid injuring the gastricwall. In addition, the width of the contact area between the gastricring and the stomach must be sufficient to avoid concentrating thepressure that is exerted on the stomach. This width is preferably atleast 1.5 cm to 2 cm.

In order to facilitate applying traction to the tie that enables theelongate element of the gastric ring to be folded into the form of aloop, it is preferable to use an ancillary 26 that is specially adapted.By way of example, the ancillary 26 is in the form of a tube 27 providedwith a handle 28 that is fitted with a mechanical system 29, inparticular a rotary or ratchet wheel 30, which engages the free ends ofthe tie that pass inside the tube 27 and that enables said free ends tobe put under tension. It then suffices to act on said handle 28 untilsaid tension enables the elongate element to be looped so as to bringthe distal and proximal end portions close together prior to fasteningthem to each other.

1. A gastric ring of the type comprising an elongate element that isdeformable into a loop between a distal end portion and a proximal endportion, and closure means suitable for folding said elongate elementinto a loop and for securing the distal and proximal end portions toeach other once they have been brought close together by looping thering, wherein at least the elongate element is made of a resorbablematerial.
 2. A gastric ring according to claim 1, wherein at least theelongate element is made of a material that is resorbable slowly over aperiod of about or less than 2 years, and preferably lying in the range16 months to 24 months.
 3. A ring according to claim 1, wherein at leastthe elongate element is made of a poly-α-hydroxy acid, preferably alactic polyacid, and more particularly a poly(L-lactide-co-D,L-lactide).
 4. A ring according to claim 1, wherein theelongate element is made up of a proximal link, a distal link, andintermediate links hinged about pivot axes.
 5. A ring according to claim4, wherein each link has an inner face for coming into contact with thestomach when the ring is put into place, and two internal end faces inwhich at least those portions that are situated close to the inner faceare oblique and radially convergent so that during closure of the ringall of said radial portions of the internal end faces are pressedagainst one another and the inner faces of the links constitute asubstantially continuous constriction surface.
 6. A ring according toclaim 5, wherein each intermediate link includes, projecting from afirst internal end face, a shoulder forming a pivot axis between saidlink and a first adjacent link, and in its second internal end face, arecess forming a housing for the shoulder of a second adjacent link, theshoulder and the recess being of dimensions to be suitable for beingmutually interengaged.
 7. A ring according to claim 1, wherein theclosure means comprise at least one tie secured to at least one of theproximal and distal end portions.
 8. A ring according to claim 7,wherein the tie is resorbable with a resorption period that is longerthan the resorption period of the elongate element.
 9. A ring accordingto claim 4, wherein each link has two through holes, together forming inthe set of links two alignments of holes for two passes of a single tiefrom the proximal link to the distal link along the first alignment andthen from the distal link to the proximal link along the secondalignment.
 10. A ring according to claim 1, wherein the closure meanscomprise locking means formed at least in part in the proximal anddistal end portions of the elongate element, in particular in theproximal and distal links, namely a male engagement element in one endportion and a female engagement element in the other end portion.
 11. Aring according to claim 10, wherein the male element is a stud and thefemale element is a recess.
 12. A ring according to claim 7, wherein theproximal end portion, possibly the proximal link, includes a tubefitting for passing the tie or the two free ends of the tie, the tubefitting being shaped for securing to an ancillary for introducing thering, and in particular being threaded for screw-fastening to saidancillary.
 13. An ancillary for introducing a ring according to claim12, being constituted by a tube provided with a handle which is fittedwith a mechanical system, in particular a winding or ratchet wheel,enabling the tie or the two free ends of the tie to be put undertension.